Electrical condenser



Aug. 5. 1924.

G.W.MCKARD ELECTRICAL CONDENSER Original Filed Oct. 8,

Patented Aug. 5, 1924.

UNITED STATES PATENT OFFICE.

GREENLEALE' WHITTIER PCKARD, 0F NEWTON CENTER, MASSACHUSETTS, ASSIGNOE T WIRELESS SPECIALTY APPARATUS COMPANY, 0F BOSTON, MASSACHUSETTS.

A CORPORATON 0F NEW YORK.

ELECTRICAL CONDENSER.

Original application filed October 8, 1920, Serial No. 415,472. Divided and this application led December Tov all whom t may concern'.-

Be it known that I, GnnENLnAr WHITTIER Premian, a citizen of the United States of America, and a resident of Newton Center,

State of Massachusetts, have invented certain new and useful Improvements in Elec trical Condensers, the principles of which are set forth in the following specification and accompanying drawings, which disclose l0 the form of the invention which l now consider to be the best of the various forms in which the principles of the invention may be embodied.

This invention relates to electrical condensers and in particular to high tension condensers for general use but especially adapted for use in radio communication.

This ap lication is a division of my application erial No. 415,472, tiled 8 @cto- *29 ber 1920.

'In condensers heretofore in use, the condenser stack has been arranged in its casing vertically, resting on the bottom and secured in the casing by meansof a cover of insulating material which has proved unsatisfactory for the purpose of maintaining the high pressure necessary for the proper operation of the condenser which requires that the sheets of dielectric, generally mica, and foil, preferably tinfoil, be maintained in intimate contact. Such condenser comprises a number of sections connected in series, the low potential section being connected to the casing, while the high potential section is connected to a suitable terminal projecting through the cover. y The object of the present invention is to provide a compact, durable ,condenser in which the stack is constantly maintained under the highest practical compression.

In particular, the object of the invention is to provide a construction in which the use of insulating material under tension for the purpose of compression of the condenser stac as heretofore, as of a top casing cover of insulatino` material, is avoided and in which the sides of the casing receive the thrust of compression, compactness being obtained by reducing to a minimum the amount of insulation used.

Furthermore, this invention is an im provement upon the disclosure of United Serial No. 677,952.

ties Patent to Dubilier No. 1,229,914 of The invention consists further in details of construction and combination of parts hereinafter more particularly described and claimed.

ln the accompanying drawings, which form a part of the speciication,

Figure l` is a sectional elevation of one embodiment of the invention;

Fig. 2 is a sectional elevation thereof taken on the line 2-2 of Fig. 1, looking in the direction of the arrows;

Fig. 3 is a sectional elevation of a modiiied form of the invention in which the casing is shown inclined; and

Fig. 4 is a sectional elevation of the construction shown in Fig. 3 taken on the line 4 4 of Fig. 3 looking in the direction of the arrows.

My co-pending application Serial Number 292,126, filed April 23, 1919, contains subject-matter disclosed in the present application, the generic features of the two applications being claimed in said application Serial Number 292,126.

In the embodiment of the invention shown in Figs. 1 and 2, there is provided a suitably strong boxlike metallic casing 1 with vertical sides 2 which are held rigid by the bottom. Within this casing is placed the stach: 2 which is arranged transversely ofy or parallel to the bottom of the casing; that is, the individual sheets of foil and dielectric composing the stack are arranged vertically with reference to the bottom and spaced therefrom sufficiently for purposes of insulation. Stack 2 may consist of one or two parts, such as parts 3 and 4, arranged end to end transversely of the bottom of the casing; that is, the individual sheets of foil and dielectric composing the stack are arranged vertically with reference to the bottom and spaced therefrom sufficiently for purposes of insulation. Stack 2 may consist of one or two parts, such as parts 3 and 4, arranged end to end transversely of the bottom of the casing, the two parts being 100 connected in parallel at adjacent ends 5 centrally ofthe casing and each part 3 and i comprising a plurality of sections 6 connected in series at alternate ends 7 and provided with separators 8 between the sec tions projecting beyond adjacent unconnected ends and beyond the connections. Means is provided in the present invention which co-operates with the sides 2a of the casing for clamping the stack in place within the casing and exerting high pressure onthe stack to maintain the sheets of dielectric and foil in intimate contact. This means in the embodiment of Fig. 1 comprises a pair of metallic wedges 9 and 10 which are placed centrally within the casing and in the present embodiment between and engaging the inner adjacent ends 5 of the two parts 3 and 4 of stack 2 and having a surface sufficiently great to cover the adjacent surfaces of the adjacent ends 5 of the two parts 3 and 4. The outer ends 11 and 12 of the stack 2 engage the vertical opposite Walls 2a of the casing 2 substantially as shown, theV stack being highly compressed between the wedges 9 and 10 and the sides of the casing, the pressure being transmitted uniformly over the entire surface of the sheets. In assembling the stack in the casing, after the wedge 9 is in place, the wedge 10 may be driven in by any suitable means compressing either the part 3 or 4, or both, against the sides 2a of the casing 1, which should be sufficiently lstrong for this purpose, thus exerting a high pressure on the stack and maintaining the sheets of foil and dielectric in intimate contact uniformly throughout their surfaces, the pressure be ing applied at right angles to the surfaces of the sheets. The inner ends 5 of the two parts 3 and 4 or the innermost sections 6 are electrically connected to the wedges 9 and 10 which constitutes a high potential oint intermediate of the stack and sufciently spaced from the casing 1 for insulation purposes. A suitable lead 13 connects these wedges 9 and 10 to a high potential terminal 14 projecting through cover 15, whereby the two parts 3 and 4 are connected in parallel. The outer ends 11 and 12 of the stack 2 are at substantially the same potential and electrically connected to the casing 1, which constitutes the low potential terminal whereby the stack may be clamped through the instrumentality of the sides of the casing without the introduction of insulation for insulating the ends from each other, although it is practicable there Ato employ under compression any of the commonly used insulating materials.

In effect, the stack 2 comprises two separate stacks or parts 3 and 4, each part having its low potential and near the casingY and its high potential point centrally of the casing. Compression is maintained on each stack or part 3 and 4 by the wedges 9 and 10 which exert a thrust on opposite walls of the casing through the two stacks or parts 3 and 4, and support the stack in its position electrically spaced from the metal .of the casing.

It will thus be seen that there is provided a stack in two parts 3 and 4, the two parts being connected in parallel and the individual sections of each part being connected in series with the outer ends 11 and 12 at the same potential as that of the casing, whereby the casing may be utilized as a part of the clamping means without excessive insulation, or insulation under tensile strains, while the central portion, the part most remote from the casing and hence suitably insulated, is the high potential point of the stack.

The stack or the parts 4 and 5 thereof may be manufactured and built up in any suitable manner, though it is preferable that they be built up of alternate sheets of foil of opposite polarity, preferably tinfoil, -and dielectric, referably mica, with proper precautions 'or removing air and moisture and highly compressing the stack during manufacture. The process may be carried out by coating each sheet with melted wax such as paraffin during the building, then submitting the stack of sheets to high pressure of the order of thousands of pounds to force out the wax, then separating the stack into sections and making the connections, then applying high pressure to the stack and treating it with wax, as more' fully described in my co-pending a plication Serial Number 380,919, filed ay 12, i920. After the stack as above treated is placed in the condenser casing 1 in the manner above described, the easing may be filled with any suitable embeddin wax 16 such as paraffin or a mixture o paraffin and carnauba wax, either with or without the aid of vacuum and the cover is then applied.

The form disclosed in Figs. 3 and 4 is slightly different from the form disclosed in Figs. 1 and 2, inasmuch as the casing 1l is there shown as having inclined sides 2", and between the outer ends 11*l and 12IL of the stack 2 and casing 1'l are placed wedges or abutments 17 and 18 of any suitable material such as metal, which also may be integral with the easing, for the purpose of providing a fiat surface for uniformly engaging the ends 11* and 12a of the stack throughout their surfaces.

Referring to Fig. 4, it will be seen that the sheets of mica 19 and foil 20 of the sections 6a taper downwardly with their long edges 21 and 22 parallel to the sides of the casing, thereby giving the sheets a vkey stone shape. The separators 8 are cut in similar manner. A uniform insulation distance between 'the edges of the foil and the casing is thus maintained. In other respects, the construction of Figs. 3 and 4 is like that of Figs. 1 and 2.

The condenser embodying thisY invention maintains the sheets of foil and dielectric in intimate contact under high pressure securing at the same time compactness and durability. In the embodiments illustrated, the outer ends of the stack or parts are at equal and low potential and electrically connected to the casing which constitutes the low potential terminal, while the intermediate part of the stack constitutes the high potential part thereof. Thus there is provided a condenser which is strong and compact and in which the stack is maintained under a high pressure Without the necessity of excessive insulation in the clamp to insulate the ends from each other.

It is to be understood that the invention is not limited to the embodiments and features specifically shown and described herein, but that such embodiments and features are subject to changes and modifications without any departure from the spirit of the invention.

Having now described the invention, what is claimed as new and what it is desired to protect by Letters Patent of the United States is as follows:

1. In a condenser, a casing, a condenser stack therein arranged transversely of the bottom of the casing, and means comprising a wedge for compressing the stach against the sides of the casing.

2. In a condenser, a metallic casing having sides, a condenser stack having parts connected in parallel, each part comprising several sections connected in series, providing ends of low potential and a centrally-located point of high potential, said ends being in proximity to the sides of the casing and at the same potential therewith, means for compressing said stack within the casing comprising a wedge exerting a thrust upon the sides of the casing, a cover for the casing and a terminal insulated by the cover and connected to the high potential point of the stack.

3. In a condenser, a metallic casing having sides, a stack comprising two parts connected in parallel, each part comprising a number of sections connected in series, providing an intermediate point of high potential and outer ends of low potential abutting against the sides of the casing, said casing being at the potential of the ends, a wedge intermediate of the two parts of the stack for forcing said two parts against the sides of the casing, said wedge being at the same potential as the adjacent high potential point of the stack, a cover and means for connecting the hi h potential point of the stack to a terminaI on the cover.

GREEILEAF WHI'ITIER PICKARD. 

